North Korea fired what appears to be multiple rocket launchers on Sunday, the South Korean military said, the latest in a series of provocations by the nuclear-armed nation.

• To read also: Shinzo Abe, a prime minister who has had a profound impact on political life in Japan

• Read also: South Korea has launched its first nationally designed space rocket

• Read also: The world is spending more and more on nuclear weapons

The South Korean military has detected "flight paths" that are likely North Korean artillery fire, the Joint Chiefs of Staff in Seoul said.

"Our military spotted flight paths suspected of being North Korean multiple rocket launchers between approximately 6:21 p.m. and 6:37 p.m. today," the staff said, without specifying. the number.

“Our military has heightened surveillance and vigilance, and maintained a thorough preparedness posture, in close cooperation with the United States,” he added.

The presidential national security office held a meeting on the shootings and said it was “closely monitoring” the situation in case of further fire from Pyongyang.

North Korea has conducted a series of weapons tests this year, including firing an intercontinental ballistic missile for the first time since 2017.

Seoul and Washington also believe that Kim Jong Un's regime could soon conduct a seventh nuclear test, which would prompt a "swift and forceful" response, warned US Assistant Secretary of State Wendy Sherman.

Last month, South Korean Defense Minister Lee Jong-sup assured that Seoul would “strengthen” its military capabilities as well as its security cooperation with Washington and Tokyo to counter the military threat from Pyongyang.

Six US F-35A fighter jets arrived in South Korea last week for a 10-day allied exercise, through July 14, in the first public deployment of US stealth warplanes to the country since late 2017.